如何在函数内部使用递归查询？

Question

我下面有一个有效的递归函数，它返回.Net元素的层次结构，在此示例中为'ImageBrush'

    WITH RECURSIVE r AS (
    SELECT id, name, dependent_id, 1 AS level
    FROM dotNetHierarchy
    WHERE name = 'ImageBrush'
    UNION ALL
    SELECT g.id, lpad(' ', r.level) || g.name, g.dependent_id, r.level + 1
    FROM dotNetHierarchy g JOIN r ON g.id = r.dependent_id
    )
    SELECT name FROM r;

现在我想在函数内部使用它，其中输入是诸如'ImageBrush'之类的文本，该文本将插入到递归查询的WHERE语句中。

表dotNetHierarchy具有3列：id，name，dependent_id

以下内容与PgAdmin一起使用，只是永远无误地进行查询：

    CREATE OR REPLACE FUNCTION get_hierarchy(inp text) RETURNS 
    TABLE (id int, name text, id int, lev int) AS
    $BODY$
    DECLARE
    BEGIN
        WITH RECURSIVE r AS (
        SELECT id, name, dependent_id, 1 AS level
        FROM dotNetHierarchy
        WHERE name = inp
      UNION ALL
        SELECT g.id, lpad(' ', r.level) || g.name, g.dependent_id, r.level + 1
        FROM dotNetHierarchy g JOIN r ON g.id = r.dependent_id
        )

        SELECT name FROM r;
        return;
    END
    $BODY$
    LANGUAGE plpgsql;

我曾尝试在Google中搜索在函数中使用递归查询的方法，但事实证明少数结果无效。

感谢您的帮助，谢谢。

Answer 1

CREATE OR REPLACE FUNCTION get_hierarchy(inp text) 
  RETURNS TABLE (id int, name text, id int, lev int) AS
$BODY$
WITH RECURSIVE r AS (
  SELECT id, name, dependent_id, 1 AS level
  FROM dotNetHierarchy
  WHERE name = inp
  UNION ALL
  SELECT g.id, lpad(' ', r.level) || g.name, g.dependent_id, r.level + 1
  FROM dotNetHierarchy g JOIN r ON g.id = r.dependent_id
)
SELECT name
FROM r;
$BODY$
LANGUAGE sql;